GoldenBlade

To use hydraulics on a Cabbie, you either move the right analog stick around, or press the left analog stick to go up and down. Pressing R3 to hop will result in starting the Taxi missions, of course. I haven't put hydraulics on a Cabbie, but this is simply common sense.

GTASAddict

Troubleshooting, you think? Wrong section, my friend. Not only is this normal on the PS2 version, it's not topic worthy, as already pointed out. And there's no way to change the control settings (not even with cheat devices), sorry. If you want to do the full throttle hop, you're going to have to find a vehicle that doesn't activate missions. Because otherwise, you'll be limited to the miniscule bounces.